import java.util.Optional;

/**
 * description: <br>
 * createTime: 2021/6/4 17:40 <br>
 *
 * @author zzh
 */
public class Test {

    public static void main(String[] args) {
        String str = null;
        String result = Optional.ofNullable(str).orElse("=======================");
        System.out.println(result);
        str = "  asjdlfk  ";
        System.out.println(str.length());
        System.out.println(str.trim().length());
        System.out.println(str.strip().length());
        System.out.println(str.stripTrailing().length());
    }
}
